The story of functionalization is really about using what is already there. A gesture, a stare, a vocalization can be used to perform a function that differs from its original context or as an extension of it. The functionalization of features is an exploitation that can either, further the propagation of a system or stabilize some aspects of it. Both strategies result from the kind of competition that is descriptive of most dynamical systems, the ability to propagate at a low energy cost in a context of limited resources. In this case, the limited resource is synaptic landscape.
Visual cues may have been replaced by vocal cues because visual cues, being indexical, fail to provide the abstract specificity and capacity for generalization required for a propagating communication system. In fact, some degree of specificity is probabilistically guaranteed just by the facts of vision in the first instance. It is likely that organisms of common stock, similarly oriented, would focus upon the same region of their visual field, and therefore to some extent share salience relations among visible cues. Certainly, whatever such visual commonalities, as there were, would underwrite the success of early diexis. But they are in themselves too neurally taxing and possibly too entrenched in individual idiosyncrasies to play any communicative roles, even with pointing. The indexicality of pointing certainly represents a decisive limitation on its playing a role in the more general propagation of information.
However pointing, and the visual capacities that underwrite its provide, is a plausible boot strap by which vocables are brought into play. Vocables are the means that allowed us to sever the ties of dependence upon indexical devices. At the same time, to say that vocables are involved so early on is already to put the matter too precipitately. There is no reason to suppose that the earliest ancestrals of linguistic vocables were not comfortable spontaneous social accompaniments, a kind of social adhesive. It may have been the later ancestry of pointing that drew from a relatively undifferentiated social soundscape, the later ancestors of words, simply by eliciting the relatively differentiated alterations that are the natural consequences of sudden motion or exertion such as grunts.
Even the soothing sounds of social bonding may be an extension of sounds that accompanied the care of children. In turn, the comforting sounds of mother may have been a continuation of feeding noises or an imitation of baby gurgles. A baby's satisfied noises after a good feed is probably the least threatening sound of all. The soundscape of hominid social habit must have been very complex indeed. It must have involved, as well, individual characteristics in vocalizations so that recognition was possible, variations between males and females, adults and young. In addition, the sheer number of members in a community influences the level of noise. Many species of birds use the stress level, created by the level of noise generated in a flock, to control their birth rate. Stress levels control the production of the number of eggs. As in the bird example, many features of hominid soundscape may have contributed to some function beyond its original occurrence. For example as throwing or hitting occurs, sudden exertion noises would have punctuated the soundscape of social interaction. These exertion noises would have promote changes in the rhythmic flow of social sounds. Moreover, the noises of things hit would have provided additional sounds that could have been used to further modify a rhythmic flow. Given a social soundscape, punctuated with peeks in vocalizations and clunking sounds of different textures being hit, the rhythmic sequencing of such features may sound like a kind of music. The non-portability of the hitting noises may have lead to the imitation of clunking noises in the absence of hitting tools or the appropriate hitting surface. This practice is still in use in music as, say, rap artists used their mouth to provide the rhythmic track that accompany the spoken words. The imitation of clunking sounds can provide the necessary contrast that is typical of rhythmic changes in linguistic noises. The sequencing of vowel-like sounds punctuated by imitations of clunking sounds is not vocabulary but may sound like a song. In fact, in many cultures, baby's first introduction to language is through the songs of its mother. For example, the Maoris of New Zealand traditionally did not talk, but sang to their young for the first six month of their lives[18]. It is feasible to think that the refinement of social soundscape provided the vowel feature in linguistic interaction and the imitation of clunking sounds provided the break in rhythm typical of the consonant feature. We can also assume that the event of consonant type noises to social soundscape most have happened much later on, maybe much after there was a kind of sequencing of vowel type noises and pointing since many ancient languages, such as Hebrew, do not script vowels at all but only consonants. The belief might have been that vowel sounds do not provide much context for an interaction as they are naturally shared in a population but that the consonant sounds are a kind of previously indexical technology that provide detail. Vocal punctuation is a pre-functional use of what would usually be part of a proto-attribution. These pre-functional vocal cues are, later on, related to prosodic flow in linguistic interaction.